A pall of smoke backs up against the Andes Mountains in South America from hundreds, possibly thousands of fires burning in the heart of the continent on September 20, 2005. The fires, most of which are likely intentional fires set by people to clear rainforest or maintain agricultural land, have been detected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite and have been marked with red dots in the image.